Permanent magnetic holding arrangements, particularly for temporary holding of ferro-magnetic work pieces are generally known.
They are comprised of at least one permanent magnet which is magnetized through its smallest thickness. Due to this magnetization the permanent magnet produces a north pole on one surface and a south pole on the opposite surface. Pole plates with good magnetic conductivity or high permeability are fixed to the pole faces of the permanent magnet. They collect the lines of flux emitted by the pole faces of the permanent magnet and conduct these to the holding surfaces.
In most cases, these permanent magnetic holding arrangements have one or two holding surfaces on which the ferro-magnetic parts, e.g. work pieces, adhere to or are held until the work process is completed. If a ferro-magnetic part is placed on the holding surfaces of the pole plates, the magnetic circuit is closed, whereby the lines of flux emitted by the north pole of the permanent magnet pass through one pole plate, through the ferro-magnetic part and return to the south pole of the permanent magnet via the other pole plate.
The strength with which the ferro-magnetic part or work piece is held on the holding surface of the arrangement depends on the size of the adhesive surface (F) linear and the induction (B) square.
If two ferro-magnetic parts are to be held on such a holding arrangement, e.g. on opposite holding surfaces, then the available magnetic flux is divided into two magnetic circuits. In the case of similar quality and nature of the hold part, only half of the magnetic induction is available for each hold part. As the induction in a square effects the holding strength, the holding strength in the case of two hold parts is reduced four-fold.